I. Field of the Invention
This invention relates generally to electrosurgical instruments for cutting and coagulating tissue, and more particularly to an instrument especially designed for cutting and sealing tubular body tissues, such as veins, fallopian tubes, vas deferens and the like.
II. Discussion of the Prior Art
In coronary bypass surgery, the bypass graft frequently comprises a segment of the great saphenous vein harvested from the patient's leg. In doing so, a surgeon would typically use a scalpel to cut longitudinally along the leg to expose the saphenous vein and then use blunt dissection techniques to remove a segment thereof which necessitates severing and subsequent coagulation of side branches emanating from the great saphenous vein to effect hemostasis before the original incision is closed. This procedure necessarily creates an extensive wound in the leg that often proves painful and slow to heal.
Less invasive techniques for harvesting the great saphenous vein have been devised and can be divided into either skin bridging or endoscopic. Skin bridging encompasses a procedure that involves making multiple incisions, ranging in length from 2 to 8 cms with retraction of the remaining overlying skin for access to the saphenous vein. Retraction is accomplished with a conventional blade-type retractor. The endoscopic technique offers an advantage of using only one or two incisions from 1 to 2 cms in length with the dissection then carried out with the assistance of an endoscope and specially designed endoscopic instruments that range in length from 24 to 45 cms. With the endoscopic technique, an instrument is used to create a tunnel around the great saphenous vein by entering a first of the transverse incisions and manipulating the instrument until its distal end is approximately midway to the adjacent incision, at which point the instrument is removed and reinserted in that adjacent incision and advanced towards the first incision until the tunnels meet. The process is then repeated along the length of the patient's leg.
While that instrument is useful in freeing the saphenous vein from adjacent connective tissue, a need exists for a companion instrument that can be used to cut and coagulate side branches emanating from the great saphenous vein. A cutting/coagulating forceps, such as that described in my earlier Rydell et al. U.S. Pat. No. 5,445,638, while readily adaptable to use in severing and sealing such branch veins is unnecessarily complex in that it requires a mechanism for manipulating the forceps jaws to make them open and close about the branch veins as well as a mechanism for actuating the cutting blade. Moreover, the scissors-style handle used on my earlier instrument is not ergonomically well suited to cutting and sealing side branches encountered when harvesting a segment of the saphenous vein for use in bypass surgery.